Numerical Sheet5

NUMERICAL SHEET 5 FUNDAMENTALS OF AUDIO SYSTEMS 1. Pressure and Intensity of sound of an automobile are 20 X 10^-3 Pa and 60dB respectively. Calculate (i) Pressure of sound for threshold of hearing (ii) Pressure of sound for normal conversation level (74 dB). (20 X 10^-6Pa, 0.1Pa) 2. Intensity of 60 dB at 100Hz give the same loudness as intensity of 40dB at 1000Hz. Calculate loudness in phon at (i)1000Hz (ii)100Hz. (40 phon) 3. Sensitivity of a microphone is 120 dB below 1 V. Calculate the output…………??????????? 4. Output of the carbon microphone is 100mV with sound pressure of 1µbar. In the absence of sound, the output reduces to 10mV. Calculate the S/N ratio. (20dB) 5. The output of a directive microphone is 0.3mV, when the output of an omnidirectional microphone placed under identical condition with respect to source is only 3µV. Calculate directivity of the two microphones in dB. (40dB) 6. Find the resistance of the amplifier if 25W output power gives 100V on the loudspeaker line. What will be the percent reduction of loss in line if the line resistance is 1Ω, and the loudspeaker resistance is 16Ω? (400Ω, 96%)